CD44v10: An Antimetastatic Membrane Glycoprotein for Pancreatic Cancer

The CD44std and CD44v9 subpopulations in non-tumorigenic invasive SNU-423 cells present different features of cancer stem cells

Hepatocellular carcinoma (HCC) is a type of liver cancer, in which CD44 isoforms have been proposed as markers to identify cancer stem cells (CSCs). However, it is unclear what characteristics are associated with CSCs that exclusively express CD44 isoforms. The objective of the present study was to determine the expression of CD44 isoforms and their properties in CSCs. Analysis of transcriptomic data from HCC patient samples identified CD44v8-10 as a potential marker in HCC. In SNU-423 cells, CD44 expression was detected in over 99% of cells, and two CD44 isoforms, namely, CD44std and CD44v9, were identified in this cell line. CD44 subpopulations, including both CD44v9+ (CD44v9) and CD44v9- (CD44std) cells, were obtained by purification using a magnetic cell separation kit for human CD44v9+ cancer stem cells. CD44v9 cells showed greater potential for colony and spheroid formation, whereas CD44std cells demonstrated significant migration and invasion capabilities. These findings suggested that CD44std and CD44v9 may be used to identify features in CSC populations and provide insights into their roles in HCC.

MiR-492 regulates metastatic properties of hepatoblastoma via CD44

BACKGROUND & AIMS

MicroRNAs are important genetic regulators of physiological and pathophysiological processes including cancer initiation and progression of hepatoblastoma, the most common liver tumour in childhood. We aimed to identify malignant and metastasis promoting effects of miR-492, a miRNA, previously reported to be overexpressed in metastatic hepatoblastoma. Furthermore, we intended to evaluate its diagnostic and prognostic potential.

METHODS

Stable and transient overexpression of miR-492 in two liver tumour cell lines HepT1 and HUH7 was used to analyse features of metastatic tumour progression such as proliferation, anchorage-independent growth, migration and invasion. Via a mass spectrometry based proteomic screen, we investigated miRNA-492-dependent effects on proteome level and explored the underlying biology. One of the predicted target genes, CD44, was experimentally validated via luciferase assays. Diagnostic and prognostic properties of miR-492 were studied in hepatoblastoma tumour samples.

RESULTS

We show that miR-492 significantly enhances cell proliferation, anchorage-independent growth, migration and invasion of hepatoblastoma cells. We also identified and validated CD44, a transmembrane adhesion receptor for hyaluronan, as direct and functional target of miR-492. This miRNA has a strong direct impact on two CD44 isoforms (standard and v10). High miR-492 expression correlates with high-risk or aggressive tumours and further bears potential for predicting reduced event-free survival.

CONCLUSIONS

We identified miR-492 and its target CD44 as regulators of a number of biological features important for malignancy and metastasis. Furthermore, we demonstrated the diagnostic and prognostic potential of miR-492, a promising novel therapeutic target and biomarker for hepatoblastoma.

The small heat shock protein αA-crystallin negatively regulates pancreatic tumorigenesis

Our recent study has shown that αA-crystallin appears to act as a tumor suppressor in pancreas. Here, we analyzed expression patterns of αA-crystallin in the pancreatic tumor tissue and the neighbor normal tissue from 74 pancreatic cancer patients and also pancreatic cancer cell lines. Immunocytochemistry revealed that αA-crystallin was highly expressed in the normal tissue from 56 patients, but barely detectable in the pancreatic tumor tissue. Moreover, a low level of αA-crystallin predicts poor prognosis for patients with pancreatic duct adenocarcinoma (PDAC). In the 12 pancreatic cell lines analyzed, except for Capan-1 and Miapaca-2 where the level of αA-crystallin was about 80% and 65% of that in the control cell line, HPNE, the remaining pancreatic cancer cells have much lower αA-crystallin levels. Overexpression of αA-crystallin in MiaPaca-1 cells lacking endogenous αA-crystallin significantly decreased its tumorigenicity ability as shown in the colony formation and wound healing assays. In contrast, knockdown of αA-crystallin in the Capan-1 cells significantly increased its tumorigenicity ability as demonstrated in the above assays. Together, our results further demonstrate that αA-crystallin negatively regulates pancreatic tumorigenesis and appears to be a prognosis biomarker for PDAC.

Phenotype and genotype of pancreatic cancer cell lines

The dismal prognosis of pancreatic adenocarcinoma is due in part to a lack of molecular information regarding disease development. Established cell lines remain a useful tool for investigating these molecular events. Here we present a review of available information on commonly used pancreatic adenocarcinoma cell lines as a resource to help investigators select the cell lines most appropriate for their particular research needs. Information on clinical history; in vitro and in vivo growth characteristics; phenotypic characteristics, such as adhesion, invasion, migration, and tumorigenesis; and genotypic status of commonly altered genes (KRAS, p53, p16, and SMAD4) was evaluated. Identification of both consensus and discrepant information in the literature suggests careful evaluation before selection of cell lines and attention be given to cell line authentication.

Splice variants as cancer biomarkers

Inherited and acquired changes in pre-mRNA splicing have been documented to play a significant role in human disease development and many cancer-associated genes are regulated by alternative splicing. Loss of fidelity, variation of the splicing process, even controlled switching to specific splicing alternatives may occur during tumor progression and could play a major role in carcinogenesis. Splice variants that are found predominantly in tumors have clear diagnostic value and may provide potential drug targets. Moreover, understanding the process of aberrant splicing and the detailed characterization of the splice variants may prove crucial to our understanding of malignant transformation. This review discusses the basic mechanism of alternative splicing, alternative splicing in cancer-associated genes, tools to identify splice variants, and the development of clinical tests based on alternatively spliced biomarkers.